git: 8b57ee7e0107 - main - sdhci_fsl_fdt: Provide more accurate clk calculation
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Date: Fri, 05 Nov 2021 09:19:21 UTC
The branch main has been updated by wma: URL: https://cgit.FreeBSD.org/src/commit/?id=8b57ee7e0107695403702cca2b5ac0dfa452b5ee commit 8b57ee7e0107695403702cca2b5ac0dfa452b5ee Author: Artur Rojek <ar@semihalf.com> AuthorDate: 2021-11-05 09:17:49 +0000 Commit: Wojciech Macek <wma@FreeBSD.org> CommitDate: 2021-11-05 09:18:57 +0000 sdhci_fsl_fdt: Provide more accurate clk calculation SDHCI controllers found in the QorIQ SoCs offer improved accuracy of the clock frequency selection, compared to the SDHCI standard. Frequency selection is performed using two divider registers, named prescaler and divisor, according to the following formula: frequency = base clock / (prescaler * divisor), where prescaler can be bypassed (set to 1) and divisor permitted to take odd values. Rather than depend on clock division precalculated by sdhci core, make use of this property of the divider registers and achieve frequencies closer to the ones requested. Obtained from: Semihalf Sponsored by: Alstom Group Differential revision: https://reviews.freebsd.org/D32706 --- sys/dev/sdhci/sdhci_fsl_fdt.c | 74 +++++++++++++++++++++++++++++++++---------- 1 file changed, 57 insertions(+), 17 deletions(-) diff --git a/sys/dev/sdhci/sdhci_fsl_fdt.c b/sys/dev/sdhci/sdhci_fsl_fdt.c index 77af367c5366..06e3afeb4b09 100644 --- a/sys/dev/sdhci/sdhci_fsl_fdt.c +++ b/sys/dev/sdhci/sdhci_fsl_fdt.c @@ -84,6 +84,7 @@ __FBSDID("$FreeBSD$"); #define SDHCI_FSL_WTMK_WR_512B (0 << 15) #define SDHCI_FSL_HOST_VERSION 0xfc +#define SDHCI_FSL_VENDOR_V23 0x13 #define SDHCI_FSL_CAPABILITIES2 0x114 #define SDHCI_FSL_TBCTL 0x120 @@ -110,6 +111,7 @@ struct sdhci_fsl_fdt_softc { uint32_t cmd_and_mode; uint16_t sdclk_bits; struct mmc_helper fdt_helper; + uint8_t vendor_ver; uint32_t (* read)(struct sdhci_fsl_fdt_softc *, bus_size_t); void (* write)(struct sdhci_fsl_fdt_softc *, bus_size_t, uint32_t); @@ -186,10 +188,26 @@ sdhci_fsl_fdt_get_clock(struct sdhci_fsl_fdt_softc *sc) return (val); } +/* + * Calculate clock prescaler and divisor values based on the following formula: + * `frequency = base clock / (prescaler * divisor)`. + */ +#define SDHCI_FSL_FDT_CLK_DIV(sc, base, freq, pre, div) \ + do { \ + (pre) = (sc)->vendor_ver < SDHCI_FSL_VENDOR_V23 ? 2 : 1;\ + while ((freq) < (base) / ((pre) * 16) && (pre) < 256) \ + (pre) <<= 1; \ + /* div/pre can't both be set to 1, according to PM. */ \ + (div) = ((pre) == 1 ? 2 : 1); \ + while ((freq) < (base) / ((pre) * (div)) && (div) < 16) \ + ++(div); \ + } while (0) + static void -fsl_sdhc_fdt_set_clock(struct sdhci_fsl_fdt_softc *sc, uint16_t val) +fsl_sdhc_fdt_set_clock(struct sdhci_fsl_fdt_softc *sc, struct sdhci_slot *slot, + uint16_t val) { - uint32_t div, freq, prescale, val32; + uint32_t prescale, div, val32; sc->sdclk_bits = val & SDHCI_DIVIDERS_MASK; val32 = RD4(sc, SDHCI_CLOCK_CONTROL); @@ -199,23 +217,16 @@ fsl_sdhc_fdt_set_clock(struct sdhci_fsl_fdt_softc *sc, uint16_t val) return; } - div = ((val >> SDHCI_DIVIDER_SHIFT) & SDHCI_DIVIDER_MASK) | - ((val >> SDHCI_DIVIDER_HI_SHIFT) & SDHCI_DIVIDER_HI_MASK) << - SDHCI_DIVIDER_MASK_LEN; - if (div == 0) - freq = sc->maxclk_hz; - else - freq = sc->maxclk_hz / (2 * div); - - for (prescale = 2; freq < sc->baseclk_hz / (prescale * 16); ) - prescale <<= 1; - for (div = 1; freq < sc->baseclk_hz / (prescale * div); ) - ++div; + /* + * Ignore dividers provided by core in `sdhci_set_clock` and calculate + * them anew with higher accuracy. + */ + SDHCI_FSL_FDT_CLK_DIV(sc, sc->baseclk_hz, slot->clock, prescale, div); #ifdef DEBUG device_printf(sc->dev, "Desired SD/MMC freq: %d, actual: %d; base %d prescale %d divisor %d\n", - freq, sc->baseclk_hz / (prescale * div), + slot->clock, sc->baseclk_hz / (prescale * div), sc->baseclk_hz, prescale, div); #endif @@ -370,7 +381,7 @@ sdhci_fsl_fdt_write_2(device_t dev, struct sdhci_slot *slot, bus_size_t off, switch (off) { case SDHCI_CLOCK_CONTROL: - fsl_sdhc_fdt_set_clock(sc, val); + fsl_sdhc_fdt_set_clock(sc, slot, val); return; /* * eSDHC hardware combines command and mode into a single @@ -689,6 +700,9 @@ sdhci_fsl_fdt_attach(device_t dev) buf_order = SDHCI_FSL_PROT_CTRL_BYTE_SWAP; } + sc->vendor_ver = (RD4(sc, SDHCI_FSL_HOST_VERSION) & + SDHCI_VENDOR_VER_MASK) >> SDHCI_VENDOR_VER_SHIFT; + sdhci_fsl_fdt_of_parse(dev); sc->maxclk_hz = host->f_max ? host->f_max : sc->baseclk_hz; @@ -803,6 +817,32 @@ sdhci_fsl_fdt_read_ivar(device_t bus, device_t child, int which, return (sdhci_generic_read_ivar(bus, child, which, result)); } +static int +sdhci_fsl_fdt_write_ivar(device_t bus, device_t child, int which, + uintptr_t value) +{ + struct sdhci_fsl_fdt_softc *sc; + struct sdhci_slot *slot = device_get_ivars(child); + uint32_t prescale, div; + + /* Don't depend on clock resolution limits from sdhci core. */ + if (which == MMCBR_IVAR_CLOCK) { + if (value == 0) { + slot->host.ios.clock = 0; + return (0); + } + + sc = device_get_softc(bus); + + SDHCI_FSL_FDT_CLK_DIV(sc, sc->baseclk_hz, value, prescale, div); + slot->host.ios.clock = sc->baseclk_hz / (prescale * div); + + return (0); + } + + return (sdhci_generic_write_ivar(bus, child, which, value)); +} + static void sdhci_fsl_fdt_reset(device_t dev, struct sdhci_slot *slot, uint8_t mask) { @@ -832,7 +872,7 @@ static const device_method_t sdhci_fsl_fdt_methods[] = { /* Bus interface. */ DEVMETHOD(bus_read_ivar, sdhci_fsl_fdt_read_ivar), - DEVMETHOD(bus_write_ivar, sdhci_generic_write_ivar), + DEVMETHOD(bus_write_ivar, sdhci_fsl_fdt_write_ivar), /* MMC bridge interface. */ DEVMETHOD(mmcbr_request, sdhci_generic_request),